Method and Apparatus for Establishing a Set of a Plurality of Synchronization Signal Sequences to be Used with One or More Communication Targets

ABSTRACT

A method and apparatus provides a determination of an expected maximum carrier frequency offset value, and a determination of a set of possible sequence values having a predetermined length, where each sequence value in the set is based upon a first maximum length sequence having a first cyclic shift, and is based upon a second maximum length sequence having a second cyclic shift. A subset of sequence values to be used as synchronization signal sequences for determining the identification of a communication target is selected from the set of possible sequence values. The selected subset of sequence values includes no more than one sequence value from any group of possible sequence values from the determined set where (a) a value of a difference between the second cyclic shift of the second maximum length sequence and the first cyclic shift of the first maximum length sequence upon which each of the possible sequence values in the group are based are equal, and (b) the difference between the respective first cyclic shift value of the first maximum length upon which each of the possible sequence values in the group are based for any two of the possible sequence values in the group are less than or equal to the determined expected maximum carrier frequency offset value. Each one of the selected subset of values is assigned to a respective one of the communication targets.

FIELD OF THE INVENTION

The present disclosure is directed to a method and apparatus for themapping of cell identities to synchronization signal sequences, and moreparticularly to the selection of a subset of sequence values to be usedwith the mapping of cell identities from a set of possible sequencevalues.

BACKGROUND OF THE INVENTION

Presently, user equipment, such as wireless communication devices,communicate with other communication devices using wireless signals,such as within a network environment that can include one or more cellswithin which various communication connections with the network andother devices operating within the network can be supported. Networkenvironments often involve one or more sets of standards, which eachdefine various aspects of any communication connection being made whenusing the corresponding standard within the network environment.Examples of developing and/or existing standards include new radioaccess technology (NR), Long Term Evolution (LTE), Universal MobileTelecommunications Service (UMTS), Global System for MobileCommunication (GSM), and/or Enhanced Data GSM Environment (EDGE).

While operating within a network, the standard will define the manner inwhich the user equipment communicates with the network includinginitiating a new connection or refreshing an existing connection thathas somehow become stale, such as for example where synchronizationbetween the user equipment and the network access point has been lost.

As part of a low level acquisition process, when attempting to initiatea connection to a network having a cellular structure, the userequipment can at least sometimes attempt to discover and acquiresignaling from each of the nearby cells. This can involve receivingcorresponding synchronization signals, which can include a respectiveprimary and a respective secondary synchronization signal. In LTE,acquisition of a primary synchronization signal is initially attemptedfrom which symbol timing and a partial cell identification can bedetermined. Various determinations of cross-correlations relative to areceived signal with each of a predetermined set of synchronizationsignals can be used to determine the likely partial cell identification,such as the physical layer identity. Further more detailed informationcan then be determined through a subsequent acquisition of a secondarysynchronization signal, including the frame timing, the rest of the cellidentity, as well as other potential communication details, such astransmission mode and/or cyclic prefix duration.

The present inventors have recognized, that the manner in which thepredetermined set of synchronization signals including the secondarysynchronization signals are selected from a list of possible sequences,and are mapped for use to the various cells and the corresponding cellidentities can determine the relative ease with which thesynchronization signal can be received and distinguished. By limitingwhich sequences can be used together including defining a mapping rulebetween a cell identity (ID) and relative cyclic shifts of multiplemaximum length sequences, the cross-correlation performance can beenhanced, so that the potential for cell ID confusion during celldetection can be reduced.

SUMMARY

Presently, user equipment, such as wireless communication devices,communicate with other communication devices using wireless signals.According to a possible embodiment, a method is provided. The methodincludes determining an expected maximum carrier frequency offset value,and determining a set of possible sequence values having a predeterminedlength, where each sequence value in the set is based upon a firstmaximum length sequence having a first cyclic shift, and is based upon asecond maximum length sequence having a second cyclic shift. A subset ofsequence values to be used as synchronization signal sequences fordetermining the identification of a communication target is selectedfrom the set of possible sequence values. The selected subset ofsequence values includes no more than one sequence value from any groupof possible sequence values from the determined set where (a) a value ofa difference between the second cyclic shift of the second maximumlength sequence and the first cyclic shift of the first maximum lengthsequence upon which each of the possible sequence values in the groupare based are equal, and (b) the difference between the respective firstcyclic shift value of the first maximum length upon which each of thepossible sequence values in the group are based for any two of thepossible sequence values in the group are less than or equal to thedetermined expected maximum carrier frequency offset value. Each one ofthe selected subset of values is assigned to a respective one of thecommunication targets.

In some embodiments, the first maximum length sequence and the secondmaximum length sequence are each a binary phase shift keying maximumlength sequence, and each of the possible sequence values is generatedvia an element-wise multiplication of the first maximum length sequencehaving a first cyclic shift and the second maximum length sequencehaving a second cyclic shift.

According to a possible embodiment, a method in a user equipment isprovided. The method includes establishing a set of a plurality ofsynchronization signal sequences to be used in connection with one ormore communication targets. Establishing the set of plurality ofsynchronization signal sequences includes determining an expectedmaximum carrier frequency offset value, and determining a set ofpossible sequence values having a predetermined length, where eachsequence value in the set is based upon a first maximum length sequencehaving a first cyclic shift, and is based upon a second maximum lengthsequence having a second cyclic shift. A subset of sequence values to beused as synchronization signal sequences for determining theidentification of a communication target is selected from the set ofpossible sequence values. The selected subset of sequence valuesincludes no more than one sequence value from any group of possiblesequence values from the determined set where (a) a value of adifference between the second cyclic shift of the second maximum lengthsequence and the first cyclic shift of the first maximum length sequenceupon which each of the possible sequence values in the group are basedare equal, and (b) the difference between the respective first cyclicshift value of the first maximum length upon which each of the possiblesequence values in the group are based for any two of the possiblesequence values in the group are less than or equal to the determinedexpected maximum carrier frequency offset value. Each one of theselected subset of values is assigned to a respective one of thecommunication targets. A downlink signal including a synchronizationsignal is received, where the synchronization signal comprises one ofthe selected subset of values included as part of the established set.The synchronization signal is then detected.

In some embodiments, an identity of a communication target is determinedat least in part from the synchronization signal, which is detected.

In some embodiments, the communication targets include one or morenetwork entities included as part of a network, where the networkentities are each respectively associated with one or more communicationareas, and where communication with the network by the user equipmentcan be facilitated via one of the one or more network entities.

In some embodiments, the communication target includes a directcommunication connection with another user equipment.

According to a possible embodiment, a user equipment in a communicationnetwork is provided. The user equipment includes a controller thatestablishes a set of a plurality of synchronization signal sequences tobe used with one or more communication targets. The plurality ofsynchronization signal sequences are identified through a determinationof an expected maximum carrier frequency offset value, and adetermination of a set of possible sequence values having apredetermined length. Each sequence value in the set is based upon afirst maximum length sequence having a first cyclic shift, and is basedupon a second maximum length sequence having a second cyclic shift,wherein a subset of sequence values to be used as synchronization signalsequences for determining the identification of each one of the one ormore communication targets are selected from the set of possiblesequence values. The selected subset of sequence values includes no morethan one sequence value from any group of possible sequence values fromthe determined set where (a) a value of a difference between the secondcyclic shift of the second maximum length sequence and the first cyclicshift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal, and (b) thedifference between the respective first cyclic shift value of the firstmaximum length upon which each of the possible sequence values in thegroup are based for any two of the possible sequence values in the groupare less than or equal to the determined expected maximum carrierfrequency offset value. Each one of the selected subset of valuesincluded as part of the established set is assigned to a respective oneof the communication targets. The user equipment further includes atransceiver that receives a downlink signal including a synchronizationsignal, where the synchronization signal comprises one of the selectedsubset of values included as part of the established set. The controllerfurther detects the synchronization signal from the received downlinksignal.

According to a possible embodiment, a method in a network entity isprovided. The method includes establishing a set of a plurality ofsynchronization signal sequences to be used in connection with one ormore communication targets. Establishing the set of plurality ofsynchronization signal sequences includes determining an expectedmaximum carrier frequency offset value, and determining a set ofpossible sequence values having a predetermined length, where eachsequence value in the set is based upon a first maximum length sequencehaving a first cyclic shift, and is based upon a second maximum lengthsequence having a second cyclic shift. A subset of sequence values to beused as synchronization signal sequences for determining theidentification of a communication target is selected from the set ofpossible sequence values. The selected subset of sequence valuesincludes no more than one sequence value from any group of possiblesequence values from the determined set where (a) a value of adifference between the second cyclic shift of the second maximum lengthsequence and the first cyclic shift of the first maximum length sequenceupon which each of the possible sequence values in the group are basedare equal, and (b) the difference between the respective first cyclicshift value of the first maximum length upon which each of the possiblesequence values in the group are based for any two of the possiblesequence values in the group are less than or equal to the determinedexpected maximum carrier frequency offset value. Each one of theselected subset of values is assigned to a respective one of thecommunication targets. A downlink signal including a synchronizationsignal is transmitted, where the synchronization signal comprises one ofthe selected subset of values included as part of the established set.

According to a possible embodiment, a network entity in a communicationnetwork is provided. The network entity includes a controller thatestablishes a set of a plurality of synchronization signal sequences tobe used with one or more communication targets. The plurality ofsynchronization signal sequences are identified through a determinationof an expected maximum carrier frequency offset value, and adetermination of a set of possible sequence values having apredetermined length. Each sequence value in the set is based upon afirst maximum length sequence having a first cyclic shift, and is basedupon a second maximum length sequence having a second cyclic shift,wherein a subset of sequence values to be used as synchronization signalsequences for determining the identification of each one of the one ormore communication targets are selected from the set of possiblesequence values. The selected subset of sequence values includes no morethan one sequence value from any group of possible sequence values fromthe determined set where (a) a value of a difference between the secondcyclic shift of the second maximum length sequence and the first cyclicshift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal, and (b) thedifference between the respective first cyclic shift value of the firstmaximum length upon which each of the possible sequence values in thegroup are based for any two of the possible sequence values in the groupare less than or equal to the determined expected maximum carrierfrequency offset value. Each one of the selected subset of valuesincluded as part of the established set is assigned to a respective oneof the communication targets. The network entity further includes atransceiver that transmits a downlink signal including a synchronizationsignal, where the synchronization signal comprises one of the selectedsubset of values included as part of the established set.

These and other objects, features, and advantages of the presentapplication are evident from the following description of one or morepreferred embodiments, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary network environment in whichthe present invention is adapted to operate;

FIG. 2 is a table of primary synchronization signal sequence tosecondary synchronization signal sequence, and secondary synchronizationsignal sequence to secondary synchronization signal sequencecross-correlation performance comparisons for two different identity tosecondary synchronization signal sequence mapping schemes;

FIG. 3 is a flow diagram of a method for establishing a set of aplurality of synchronization signal sequences to be used in determiningthe identification of a communication target;

FIG. 4 is a flow diagram in a user equipment for receiving a mappedsynchronization signal sequence;

FIG. 5 is a flow diagram in a network entity for transmitting a mappedsynchronization signal sequence; and

FIG. 6 is an example block diagram of an apparatus according to apossible embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

While the present disclosure is susceptible of embodiment in variousforms, there is shown in the drawings and will hereinafter be describedpresently preferred embodiments with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentsillustrated.

Embodiments provide a method and apparatus for mapping of cellidentities to synchronization signal sequences.

FIG. 1 is an example block diagram of a system 100 according to apossible embodiment. The system 100 can include a wireless communicationdevice 110, such as User Equipment (UE), a base station 120, such as anenhanced NodeB (eNB) or next generation NodeB (gNB), and a network 130.The wireless communication device 110 can be a wireless terminal, aportable wireless communication device, a smartphone, a cellulartelephone, a flip phone, a personal digital assistant, a personalcomputer, a selective call receiver, a tablet computer, a laptopcomputer, or any other device that is capable of sending and receivingcommunication signals on a wireless network.

The network 130 can include any type of network that is capable ofsending and receiving wireless communication signals. For example, thenetwork 130 can include a wireless communication network, a cellulartelephone network, a Time Division Multiple Access (TDMA)-based network,a Code Division Multiple Access (CDMA)-based network, an OrthogonalFrequency Division Multiple Access (OFDMA)-based network, a Long TermEvolution (LTE) network, a 5th generation (5G) network, a 3rd GenerationPartnership Project (3GPP)-based network, a satellite communicationsnetwork, a high altitude platform network, the Internet, and/or othercommunications networks.

In a fifth generation (5G) radio access technology (RAT) based wirelessnetwork, the number of cells generally meaningfully increases for areacapacity enhancement and for use of high frequency bands. Thus,synchronization signal (SS) sequences carrying cell identities (ID)should have good cross-correlation performances to allow flexiblenetwork deployment without complex cell ID planning and for reducingpotential cell ID confusion at a user equipment (UE). Furthermore, thecross-correlation performance should be robust to carrier frequencyoffset (CFO), as the UE has to detect the SS sequences without perfecttiming and frequency synchronization.

In 3GPP new RAT (NR), three primary synchronization signal (PSS)sequences were defined as follows:

-   -   frequency domain-based pure binary phase shift keying (BPSK)        maximum length sequence (M sequence)        -   1 polynomial: decimal 145 (i.e. g(x)=x⁷+x⁴+1)        -   3 cyclic shifts (0, 43, 86) in the frequency domain to get            the 3 PSS sequences        -   Initial polynomial shift register values: 1110110

According to 3GPP TS 38.211 V15.0.0, the sequence d_(PSS)(n) for theprimary synchronization signal is defined by

d _(PSS)(n)=1−2×(m)

m=(n+43N _(ID) ⁽²⁾)mod 127

0≤n<127

where N_(ID) ⁽²⁾ is a PSS sequence index,

x(i+7)=(x(i+4)+x(i))mod 2

and

[x(6)x(5)x(4)x(3)x(2)x(1)x(0)]=[11110110].

Secondary synchronization signal (SSS) sequences can be generated viaelement-wise multiplication of two BPSK m-sequences, each with its owncyclic shift. If two generator polynomials for m-sequences arepreferred-pair of m-sequences, the SSS sequences are Gold sequences andtheir cyclic shifts. For example, two generator polynomials can beg₀(x)=x⁷+x⁴+1 and g₁(x)=x⁷+x+1 with initial state [0000001]. Consideringthat residual CFO due to estimation error and/or high Doppler spread mayexist even after PSS based CFO estimation and compensation, SSSsequences should have good cross-correlation performances at least underCFO of up to +/−0.5 subcarrier spacing.

This present disclosure presents methods to select a set of SSSsequences, such as from given Gold sequences and their cyclic shifts,which has robust cross-correlation performances under CFO, by defining aproper mapping rule between a cell ID and cyclic shifts of twom-sequences used for the Gold sequences.

The mapping of a cell ID to a SSS sequence in at least some alternativeinstances including according to the proposal in the referenceR1-1708160, entitled “Remaining details for synchronization signals”,shown below, may cause cell ID confusion at UE with residual CFO inmulti-cell environments.

${m_{0} = {{3 \cdot \left\lfloor \frac{N_{ID}^{(1)}}{112} \right\rfloor} + N_{ID}^{(2)}}},{m_{1} = {\left( {N_{ID}^{(1)}\mspace{14mu} {mod}\; 112} \right) + m_{0} + 1}},$

where N_(ID) ^(cell)=N_(ID) ⁽¹⁾·3+N_(ID) ⁽²⁾, where N_(id) ⁽²⁾=0, 1, 2and N_(id) ⁽¹⁾=0, 1, . . . , 335.

This is because the proposed mapping in said identified proposal, namelyR1-1708160, generates one or more SSS sequence pairs, wherein, in eachSSS sequence pair, one sequence is 1-cyclic shift of the other sequence.

According to a possible embodiment of the present application, thelength-L SSS sequences d(0), . . . , d(L−1) based on 2 preferred-pairm-sequences can be described as follows:

d(n)=1−2(c ₀ ^((m) ⁰ ⁾(n)+c ₁ ^((m) ¹ ⁾(n))mod 2), n=0,1, . . .,L−1,  (1)

where

c ₀ ^((m) ⁰ ⁾(n)=s ₀((n+m ₀)mod L),

c ₁ ^((m) ¹ ⁾(n)=s ₁((n+m ₁)mod L),

and s₀(n) and s₁(n) are two m-sequences, for example, with generatorpolynomials g₀(x)=x⁷+x⁴+1 and g₁(x)=x⁷+x+1, respectively, and initialstate [0000001]. The cyclic shift values m₀ and m₁ are determined by acell ID, N_(ID) ^(cell), which is a function of an NR PSS sequence indexN_(ID) ⁽²⁾ and an NR SSS sequence index N_(id) ⁽¹⁾, for example, n_(ID)^(CELL)=n_(ID) ⁽¹⁾·3+n_(ID) ⁽²⁾, where N_(ID) ⁽²⁾=0, 1, 2 and N_(ID)⁽¹⁾=0, 1, . . . , 335. Equivalently, the sequence d(n) for the secondarysynchronization signal can be described as element-wise multiplicationof two BPSK m-sequences as follows:

d(n)=[1−2x ₀((n+m ₀)mod L)][1−2x ₁((n+m ₁)mod L)]

0≤n<L

where

x ₀(i+7)=(x ₀(i+4)+x ₀(i))mod 2

x ₁(i+7)=(x ₁(i+1)+x ₁(i))mod 2

and

[x ₀(6)x ₀(5)x ₀(4)x ₀(3)x ₀(2)x ₀(1)x ₀(0)]=[0000001]

[x ₁(6)x ₁(5)x ₁(4)x ₁(3)x ₁(2)x ₁(1)x ₁(0)]=[0000001]

In one embodiment, any two SSS sequences having the common (m₁−m₀) valuehave two different m₀ values, wherein m₁ is larger than m₀, and amagnitude of a difference of the two m₀ values is larger than a firstvalue, wherein the first value is dependent on the maximum allowed (orexpected) residual CFO. In one example, the first value is the nearestinteger larger than a magnitude of the maximum allowed (or expected)residual CFO. In equation (1), a unique SSS sequence is determined bythe values m₀ and (m₁−m₀), where m₀=0, 1, . . . , L−1, and m₁−m₀=0, 1, .. . , L−1. Thus, the total number of unique sequences which can begenerated from the above equation (1) are L². Further, L sequences fromL pairs of (m₀, m₁), which result in the same (m₁−m₀) value, are Lcyclic shifted versions of one sequence. Assuming that the above SSSsequences are directly mapped to consecutive subcarriers in thefrequency domain, any two SSS sequences which are 1-cyclic shift of eachother may suffer from high cross-correlation in frequency domain due toresidual CFO up to +/−0.5 subcarrier spacing, wherein the subcarrierspacing refers to the subcarrier spacing of PSS and SSS. Thus, among aset of SSS sequences, any two SSS sequences having the common (m₁−m₀)value should have 2 or larger difference for the m₀ value so that thetwo SSS sequences are two or more cyclic shifts of each other.

In one example, cyclic shifts m₀ and m₁ applied to generate a SSSsequence are determined as follows:

${m_{0} = {{{ab} \cdot \left\lfloor \frac{N_{ID}^{(1)}}{\left\lceil {c\text{/}b} \right\rceil} \right\rfloor} + {a \cdot N_{ID}^{(2)}}}},{m_{1} = {\left( {N_{ID}^{(1)}\mspace{14mu} {mod}\left\lceil {c\text{/}b} \right\rceil} \right) + m_{0} + 1}},$

where a is the nearest integer larger than a magnitude of the maximumallowed (or expected) residual CFO, b is the number of PSS IDs, c is thenumber of SSS IDs. For 1008 cell IDs with 3 PSS IDs and 336 SSS IDs andthe residual CFO up to +/−0.5 subcarrier spacing (i.e. frequencyuncertainty of up to 1 subcarrier spacing), cyclic shifts m₀ and m₁ fora length-127 SSS sequence are determined as follows:

$\begin{matrix}{{m_{0} = {{6 \cdot \left\lfloor \frac{N_{ID}^{(1)}}{112} \right\rfloor} + {2 \cdot N_{ID}^{(2)}}}},} & (2) \\{m_{1} = {\left( {N_{ID}^{(1)}\mspace{14mu} {mod}\; 112} \right) + m_{0} + 1}} & (3)\end{matrix}$

In another example, cyclic shifts m₀ and m₁ for a length-L SSS sequenceis determined as follows:

${m_{0} = {a \cdot \left\lfloor \frac{N_{ID}^{cell}}{L} \right\rfloor}},{m_{1} = {\left( {N_{ID}^{cell}\mspace{14mu} {mod}\; L} \right) + m_{0}}},$

where the cell ID N_(ID) ^(cell) is a function of a PSS ID and a SSS ID,and a is the nearest integer larger than a magnitude of the maximumallowed (or expected) residual CFO. In an alternative example,

${m_{0} = {{{a \cdot b}\left\lfloor \frac{N_{ID}^{(1)}}{L} \right\rfloor} + {a \cdot N_{ID}^{(2)}}}},{m_{1} = {\left( {N_{ID}^{(1)}\mspace{14mu} {mod}\; L} \right) + m_{0}}},$

where a is the nearest integer larger than a magnitude of the maximumallowed (or expected) residual CFO, b is the number of PSS IDs.

FIG. 2 is a table 200 of primary synchronization signal sequence tosecondary synchronization signal sequence, and secondary synchronizationsignal sequence to secondary synchronization signal sequencecross-correlation performance comparisons for two different identity tosecondary synchronization signal sequence mapping schemes. In theillustrated table, PSS-SSS and SSS-SSS cross-correlation performancesare presented for two different cell ID to SSS sequence mapping schemes.The first row 210 represents the performance in accordance with thecited reference, R1-1708160, and the second row 220 represents theperformance in accordance with equations (2) and (3) in accordance withthe teachings of at least one embodiment of the present application.

In the table, a first column 230 corresponds to a maximum primarysynchronization signal sequence to secondary synchronization signalsequence cross-correlation power normalized by peak primarysynchronization signal sequence auto-correlation power with multipleinteger carrier frequency offset hypothesis for a network having 1008cell IDs, and a carrier frequency offset in the range of −3 to 3sub-carrier spacing with a correlation in the time-domain. A secondcolumn 240 corresponds to a maximum secondary synchronization signalsequence cross-correlation power normalized by secondary synchronizationsignal sequence auto-correlation power with carrier frequency offset fora network having 1008 cell IDs, and a carrier frequency offset in therange of −0.5 to 0.5 sub-carrier spacing with a correlation in thefrequency-domain.

In the table, it is shown that the proposed mapping according toequations (2) and (3) can avoid high SSS cross-correlation, while themapping scheme in the above noted reference, R1-1708160, suffers from anormalized SSS cross-correlation power close to 1. The proposed mappingaccording to equations (2) and (3) noted above related to the teachingsof at least one embodiment of the present application alternativelyproduces a normalized SSS cross-correlation power, which isapproximately 0.4246.

FIG. 3 is a flow diagram 300 of a method for establishing a set of aplurality of synchronization signal sequences to be used in determiningthe identification of a communication target, according to a possibleembodiment. The method provides for determining 302 an expected maximumcarrier frequency offset value, and determining 304 a set of possiblesequence values having a predetermined length, where each sequence valuein the set is based upon a first maximum length sequence having a firstcyclic shift, and is based upon a second maximum length sequence havinga second cyclic shift. A subset of sequence values to be used assynchronization signal sequences for determining the identification of acommunication target is selected 306 from the set of possible sequencevalues. The selected subset of sequence values includes no more than onesequence value from any group of possible sequence values from thedetermined set where (a) a value of a difference between the secondcyclic shift of the second maximum length sequence and the first cyclicshift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal 308, and (b)the difference between the respective first cyclic shift value of thefirst maximum length upon which each of the possible sequence values inthe group are based for any two of the possible sequence values in thegroup are less than or equal to the determined expected maximum carrierfrequency offset value 310. Each one of the selected subset of valuesare then assigned 312 to a respective one of the communication targets.

In at least some instances, the first maximum length sequence and thesecond maximum length sequence are each a binary phase shift keyingmaximum length sequence, and each of the possible sequence values isgenerated via an element-wise multiplication of the first maximum lengthsequence having a first cyclic shift and the second maximum lengthsequence having a second cyclic shift. In some of the same or otherinstances, the communication targets can include one or more networkentities included as part of a network, where the network entities areeach respectively associated with one or more communication areas, andwhere communication with the network can be facilitated via one of theone or more network entities.

In some instances, the selected subset of sequence values can berespectively associated with a secondary synchronization signal, wherethe secondary synchronization signal is mapped and transmitted onconsecutive subcarriers in a frequency domain. In some of theseinstances, a primary synchronization signal associated with thecommunication target can be used with the secondary synchronizationsignal to determine a physical identity value for the communicationtarget, where in addition to a physical identity value for thecommunication target, the primary synchronization signal and thesecondary synchronization signal associated with a particularcommunication target can be used to determine at least somecommunication characteristics for use with subsequent communicationswith the communication target.

FIG. 4 is a flow diagram 400 in a user equipment for receiving a mappedsynchronization signal sequence. The method includes establishing a setof a plurality of synchronization signal sequences to be used inconnection with one or more communication targets. In at least someinstances, the set of plurality of synchronization signal sequences canbe established 300 as outlined in FIG. 3, including the subsequentassignment of each one of the selected subset of values included as partof the established set to a respective one of the communication targets.The downlink signal including a synchronization signal is then received402, where the synchronization signal comprises one of the selectedsubset of values included as part of the established set. Thesynchronization signal is then detected 404.

In some instances, an identity of a communication target can bedetermined 406 at least in part from the synchronization signal, whichis detected.

In some instances, the selected subset of sequence values can berespectively associated with a secondary synchronization signal, wherethe secondary synchronization signal is mapped and transmitted onconsecutive subcarriers in a frequency domain. In some of theseinstances, a primary synchronization signal associated with thecommunication target can be used with the secondary synchronizationsignal to determine a physical identity value for the communicationtarget, where in addition to a physical identity value for thecommunication target, the primary synchronization signal and thesecondary synchronization signal associated with a particularcommunication target can be used to determine 408 at least somecommunication characteristics for use with subsequent communicationswith the communication target.

In some of the same or other instances, the first maximum lengthsequence and the second maximum length sequence are each a binary phaseshift keying maximum length sequence, and each of the possible sequencevalues can be generated via an element-wise multiplication of the firstmaximum length sequence having a first cyclic shift and the secondmaximum length sequence having a second cyclic shift.

The communication targets can include one or more network entitiesincluded as part of a network, where the network entities are eachrespectively associated with one or more communication areas, and wherecommunication with the network by the user equipment can be facilitatedvia one of the one or more network entities. The communication targetcan additionally and/or alternatively include a direct communicationconnection with another user equipment.

FIG. 5 is a flow diagram 500 in a network entity for transmitting amapped synchronization signal sequence. The method similar to the flowdiagram illustrated in FIG. 4, can include establishing a set of aplurality of synchronization signal sequences to be used in connectionwith one or more communication targets. In at least some instances, theset of plurality of synchronization signal sequences can be established300 as outlined in FIG. 3, including the subsequent assignment of eachone of the selected subset of values included as part of the establishedset to a respective one of the communication targets. The downlinksignal including a synchronization signal is then transmitted 502, wherethe synchronization signal comprises one of the selected subset ofvalues included as part of the established set.

It should be understood that, notwithstanding the particular steps asshown in the figures, a variety of additional or different steps can beperformed depending upon the embodiment, and one or more of theparticular steps can be rearranged, repeated or eliminated entirelydepending upon the embodiment. Also, some of the steps performed can berepeated on an ongoing or continuous basis simultaneously while othersteps are performed. Furthermore, different steps can be performed bydifferent elements or in a single element of the disclosed embodiments.

FIG. 6 is an example block diagram of an apparatus 600, such as thewireless communication device 110, according to a possible embodiment.The apparatus 600 can include a housing 610, a controller 620 within thehousing 610, audio input and output circuitry 630 coupled to thecontroller 620, a display 640 coupled to the controller 620, atransceiver 650 coupled to the controller 620, an antenna 655 coupled tothe transceiver 650, a user interface 660 coupled to the controller 620,a memory 670 coupled to the controller 620, and a network interface 680coupled to the controller 620. The apparatus 600 can perform the methodsdescribed in all the embodiments

The display 640 can be a viewfinder, a liquid crystal display (LCD), alight emitting diode (LED) display, a plasma display, a projectiondisplay, a touch screen, or any other device that displays information.The transceiver 650 can include a transmitter and/or a receiver. Theaudio input and output circuitry 630 can include a microphone, aspeaker, a transducer, or any other audio input and output circuitry.The user interface 660 can include a keypad, a keyboard, buttons, atouch pad, a joystick, a touch screen display, another additionaldisplay, or any other device useful for providing an interface between auser and an electronic device. The network interface 680 can be aUniversal Serial Bus (USB) port, an Ethernet port, an infraredtransmitter/receiver, an IEEE 1394 port, a WLAN transceiver, or anyother interface that can connect an apparatus to a network, device, orcomputer and that can transmit and receive data communication signals.The memory 670 can include a random access memory, a read only memory,an optical memory, a solid state memory, a flash memory, a removablememory, a hard drive, a cache, or any other memory that can be coupledto an apparatus.

The apparatus 600 or the controller 620 may implement any operatingsystem, such as Microsoft Windows®, UNIX®, or LINUX®, Android™, or anyother operating system. Apparatus operation software may be written inany programming language, such as C, C++, Java or Visual Basic, forexample. Apparatus software may also run on an application framework,such as, for example, a Java® framework, a .NET® framework, or any otherapplication framework. The software and/or the operating system may bestored in the memory 670 or elsewhere on the apparatus 600. Theapparatus 600 or the controller 620 may also use hardware to implementdisclosed operations. For example, the controller 620 may be anyprogrammable processor. Disclosed embodiments may also be implemented ona general-purpose or a special purpose computer, a programmedmicroprocessor or microprocessor, peripheral integrated circuitelements, an application-specific integrated circuit or other integratedcircuits, hardware/electronic logic circuits, such as a discrete elementcircuit, a programmable logic device, such as a programmable logicarray, field programmable gate-array, or the like. In general, thecontroller 620 may be any controller or processor device or devicescapable of operating an apparatus and implementing the disclosedembodiments. Some or all of the additional elements of the apparatus 600can also perform some or all of the operations of the disclosedembodiments.

The method of this disclosure can be implemented on a programmedprocessor. However, the controllers, flowcharts, and modules may also beimplemented on a general purpose or special purpose computer, aprogrammed microprocessor or microcontroller and peripheral integratedcircuit elements, an integrated circuit, a hardware electronic or logiccircuit such as a discrete element circuit, a programmable logic device,or the like. In general, any device on which resides a finite statemachine capable of implementing the flowcharts shown in the figures maybe used to implement the processor functions of this disclosure.

While this disclosure has been described with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. For example,various components of the embodiments may be interchanged, added, orsubstituted in the other embodiments. Also, all of the elements of eachfigure are not necessary for operation of the disclosed embodiments. Forexample, one of ordinary skill in the art of the disclosed embodimentswould be enabled to make and use the teachings of the disclosure bysimply employing the elements of the independent claims. Accordingly,embodiments of the disclosure as set forth herein are intended to beillustrative, not limiting. Various changes may be made withoutdeparting from the spirit and scope of the disclosure.

In this document, relational terms such as “first,” “second,” and thelike may be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. The phrase“at least one of,”” “at least one selected from the group of,” or “atleast one selected from” followed by a list is defined to mean one,some, or all, but not necessarily all of, the elements in the list. Theterms “comprises,” “comprising,” “including,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element proceeded by “a,” “an,” or the like does not,without more constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element. Also, the term “another” is defined as at least a second ormore. The terms “including,” “having,” and the like, as used herein, aredefined as “comprising.” Furthermore, the background section is writtenas the inventor's own understanding of the context of some embodimentsat the time of filing and includes the inventor's own recognition of anyproblems with existing technologies and/or problems experienced in theinventor's own work.

What is claimed is:
 1. A method comprising: determining an expectedmaximum carrier frequency offset value; determining a set of possiblesequence values having a predetermined length, where each sequence valuein the set is based upon a first maximum length sequence having a firstcyclic shift, and is based upon a second maximum length sequence havinga second cyclic shift; selecting from the set of possible sequencevalues a subset of sequence values to be used as synchronization signalsequences for determining the identification of a communication target,the selected subset of sequence values including no more than onesequence value from any group of possible sequence values from thedetermined set where (a) a value of a difference between the secondcyclic shift of the second maximum length sequence and the first cyclicshift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal, and (b) thedifference between the respective first cyclic shift value of the firstmaximum length upon which each of the possible sequence values in thegroup are based for any two of the possible sequence values in the groupare less than or equal to the determined expected maximum carrierfrequency offset value; and assigning each one of the selected subset ofvalues to a respective one of the communication targets.
 2. A method inaccordance with claim 1, wherein the first maximum length sequence andthe second maximum length sequence are each a binary phase shift keyingmaximum length sequence, and each of the possible sequence values isgenerated via an element-wise multiplication of the first maximum lengthsequence having a first cyclic shift and the second maximum lengthsequence having a second cyclic shift.
 3. A method in accordance withclaim 1, wherein the communication targets include one or more networkentities included as part of a network, where the network entities areeach respectively associated with one or more communication areas, andwhere communication with the network can be facilitated via one of theone or more network entities.
 4. A method in accordance with claim 1,wherein the selected subset of sequence values are respectivelyassociated with a secondary synchronization signal.
 5. A method inaccordance with claim 4, wherein the secondary synchronization signal ismapped and transmitted on consecutive subcarriers in a frequency domain.6. A method in accordance with claim 4, wherein a primarysynchronization signal associated with the communication target is usedwith the secondary is synchronization signal to determine a physicalidentity value for the communication target.
 7. A method in accordancewith claim 6, where in addition to a physical identity value for thecommunication target, the primary synchronization signal and thesecondary synchronization signal associated with a particularcommunication target can be used to determine at least somecommunication characteristics for use with subsequent communicationswith the communication target.
 8. A method in a user equipment, themethod comprising: establishing a set of a plurality of synchronizationsignal sequences to be used in connection with one or more communicationtargets, where establishing the set of plurality of synchronizationsignal sequences includes determining an expected maximum carrierfrequency offset value; determining a set of possible sequence valueshaving a predetermined length, where each sequence value in the set isbased upon a first maximum length sequence having a first cyclic shift,and is based upon a second maximum length sequence having a secondcyclic shift; selecting from the set of possible sequence values asubset of sequence values to be included as part of the established set,the selected subset of sequence values including no more than onesequence value from any group of possible sequence values from thedetermined set where (a) a value of a difference between the secondcyclic shift of the second maximum length sequence and the first cyclicshift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal, and (b) thedifference between the respective first cyclic shift value of the firstmaximum length upon which each of the possible sequence values in thegroup are based for any two of the possible sequence values in the groupare less than or equal to the determined expected maximum carrierfrequency offset value; assigning each one of the selected subset ofvalues included as part of the established set to a respective one ofthe communication targets; receiving a downlink signal including asynchronization signal, where the synchronization signal comprises oneof the selected subset of values included as part of the establishedset; and detecting the synchronization signal.
 9. A method in accordancewith claim 8, further comprising determining an identity of acommunication target at least in part from the synchronization signal,which is detected.
 10. A method in accordance with claim 8, wherein theassigned one of the selected subset of sequence values associated with acommunication target is related to a corresponding secondarysynchronization signal, which can be detected.
 11. A method inaccordance with claim 10, wherein a primary synchronization signalcorresponding to the communication target is used by the user equipmentwith the secondary synchronization signal to determine a physicalidentity value for the communication target.
 12. A method in accordancewith claim 10, wherein the secondary synchronization signal is mappedand transmitted on consecutive subcarriers in a frequency domain.
 13. Amethod in accordance with claim 12, where in addition to a physicalidentity value for the communication target, the primary synchronizationsignal and the secondary synchronization signal associated with aparticular communication target can be used to determine at least somecommunication characteristics for use with subsequent communicationsbetween the user equipment and the communication target.
 14. A method inaccordance with claim 8, wherein the first maximum length sequence andthe second maximum length sequence are each a binary phase shift keyingmaximum length sequence, and each of the possible sequence values isgenerated via an element-wise multiplication of the first maximum lengthsequence having a first cyclic shift and the second maximum lengthsequence having a second cyclic shift.
 15. A method in accordance withclaim 8, wherein the communication targets include one or more networkentities included as part of a network, where the network entities areeach respectively associated with one or more communication areas, andwhere communication with the network by the user equipment can befacilitated via one of the one or more network entities.
 16. A method inaccordance with claim 8, wherein the communication target includes adirect communication connection with another user equipment.
 17. A userequipment in a communication network, the user equipment comprising: acontroller that establishes a set of a plurality of synchronizationsignal sequences to be used with one or more communication targets,where the plurality of synchronization signal sequences are identifiedthrough a determination of an expected maximum carrier frequency offsetvalue, and a determination of a set of possible sequence values having apredetermined length, where each sequence value in the set is based upona first maximum length sequence having a first cyclic shift, and isbased upon a second maximum length sequence having a second cyclicshift, wherein a subset of sequence values to be used as synchronizationsignal sequences for determining the identification of each one of theone or more communication targets are selected from the set of possiblesequence values, the selected subset of sequence values including nomore than one sequence value from any group of possible sequence valuesfrom the determined set where (a) a value of a difference between thesecond cyclic shift of the second maximum length sequence and the firstcyclic shift of the first maximum length sequence upon which each of thepossible sequence values in the group are based are equal, and (b) thedifference between the respective first cyclic shift value of the firstmaximum length upon which each of the possible sequence values in thegroup are based for any two of the possible sequence values in the groupare less than or equal to the determined expected maximum carrierfrequency offset value, and wherein each one of the selected subset ofvalues included as part of the established set is assigned to arespective one of the communication targets; and a transceiver thatreceives a downlink signal including a synchronization signal, where thesynchronization signal comprises one of the selected subset of valuesincluded as part of the established set; and wherein the controllerfurther detects the synchronization signal from the received downlinksignal.
 18. A user equipment in accordance with claim 17, wherein thecommunication target includes a network comprising one or more networkentities respectively associated with one or more communication areas,and the user equipment communicates with the network via the one or morenetwork entities.
 19. A user equipment in accordance with claim 18,wherein the controller uses the detected synchronization signal toidentify at least a partial physical-layer cell identity of one of theone or more network entities.
 20. A user equipment in accordance withclaim 17, wherein the communication target includes a directcommunication connection with another user equipment.